This invention relates to the filtration field, and more particularly, to an improved low hold up biological fluid filtration system, including a low hold up double sided biological fluid filter device lacking a partition wall capable of filtering biological fluids, including the removal of components or chemicals from blood or blood products, and including the removal of leukocytes from packed red cells, and prions from blood or blood products.
Double sided biological fluid filtration devices that include a single inlet and a single outlet with a partition wall are disclosed in patent serial no. U.S. Pat. No. 6,660,171 B2, entitled HIGH CAPACITY GRAVITY FEED FILTER FOR FILTERING BLOOD AND BLOOD PRODUCTS, filed on Mar. 27, 2001 which is hereby incorporated by reference and made a part of the disclosure herein. Double sided biological fluid filtration devices that contain a partition wall are also disclosed in patent application Ser. No. 10/934,881, entitled A BIOLOGICAL FLUID FILTRATION APPARATUS, filed on Sep. 3, 2004 which is hereby incorporated by reference and made a part of the disclosure herein. Double sided biological fluid filtration devices that contain a partition wall are also disclosed in PCT application no. PCT/US2004/029026, entitled A BIOLOGICAL FLUID FILTRATION APPARATUS, filed on Sep. 7, 2004 which is hereby incorporated by reference and made a part of the disclosure herein. Application Ser. No. 10/934,881 and application no. PCT/US2004/029026 disclose a double sided biological fluid filtration device that includes two independent fluid flow paths separated by a partition wall with each fluid flow path containing a separate inlet and outlet, thereby allowing two units of biological fluid including blood or blood product to be independently filtered.
U.S. Pat. No. 6,231,770 B1 describes a double sided biological fluid filtration device that lacks a partition wall that includes a single inlet and a single outlet with two fluid flow paths between the inlet and outlet. The disadvantage of this type of device is that if two units of blood or blood product are filtered through this device and collected into two separate receiving blood bags, the first unit will be filtered by the device with the filter elements of the device in a relatively non-fouled condition, and the second unit will be filtered by the device with the filter elements in a relatively fouled condition. Therefore the flow rate through the device for the first unit will be faster than the flow rate for the second unit. Hence the filtration efficiency may be different between the first and second units, and when the device is used for leukocyte reduction the leukocyte reduction rate may be different for the first and second units.
It is therefore an object of the present invention to provide a biological fluid filtration system including a biological fluid filtration device that lacks a partition wall, and that includes a single inlet and a double outlet, that will filter two units of biological fluid including blood or blood product, with both units being filtered simultaneously at approximately the same flow rate, and that will run automatically, and minimize hold up volume. It is also an object of the present invention to provide a single vent filtration device that can vent the two fluid flow paths of a biological fluid filtration device that includes two independent fluid flow paths.